The Big Chest is a special Chest that is always found somewhere in The Mines, on any level except the first level and dark levels. It contains the Udjat Eye, an item used to find The Black Market and access to the City of Gold. It can only be opened by finding the Key required to unlock it, which is always placed somewhere on the same level as the chest. The chest will always spawn in the main path or adjacent rooms, but the Key can be generated anywhere in the level.